JPH0687738B2 - Method and apparatus for withered fermented tea leaves - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application The present invention mainly relates to a method and apparatus for wilt fermentation of fresh tea leaves when producing oolong tea.

b. Conventional technology Oolong tea is a general term for semi-fermented tea, and it lies between black tea that is completely fermented and green tea that is not fermented at all.
It is manufactured in the following order.

1) Directly expose the fresh tea leaves to sunlight and occasionally invert the fresh tea leaves, and then wither the sun. 2) Introduce it indoors and spread it in a place where ventilation is not severe. From time to time, invert the fresh tea leaves to wither the indoors. 3 ) When the periphery of the fresh tea leaves has turned reddish brown, put it in a high-temperature kettle and perform "roasting" for several minutes, 4) knead for several tens of minutes, 5) loosen the lumps, and dry sufficiently.

c. Problems to be Solved by the Invention Among the above-mentioned manufacturing methods, the withering of 1) and 2) is performed by manpower for a long time while adjusting the degree thereof depending on the weather. Therefore, it is not suitable for the Japanese tea industry, which aims for large-scale processing with a small number of people, and the degree of withering and fermentation greatly depends on the weather of the day, and it is difficult to produce tea of uniform quality.

The present invention compensates for the drawbacks of the conventional wilting / fermenting method as described above, that is, to provide a method and an apparatus for homogeneously withering and fermenting a large amount of fresh tea leaves in a short time regardless of the weather. With the goal.

d. Means for Solving the Problems In order to achieve the above object, the first invention is to supply a small amount of hot air while exhausting the hot air from the other side.
Keeping the room temperature of about ℃, spread the tea leaves thinly in the space, so that the product temperature will be around 30 ~ 50 ℃ by the far infrared heater that can evenly radiate this tea leaf surface The tea leaves are heated to promote wilting and fermentation of the tea leaves, and then a predetermined amount of such tea leaves are collected, and the fermentation is further promoted by rotating and stirring at once.

Similarly, the second aspect of the present invention is provided with a tea leaf input port on one side and an outlet port on the other side, and is internally provided with a transfer means for transferring the tea leaves while spreading them thinly, and the surface of the transfer means is uniformly radiated. A means for withering / fermenting fresh tea leaves equipped with a far-infrared heater that can be operated and a hot air generator capable of supplying a small amount of hot air, and a pool for holding the tea leaves withdrawn from the withering means until a predetermined amount is reached. And a fermenting means in which a cylindrical rotating drum for accommodating a predetermined amount of tea leaves in the pool is horizontally installed and a stirring bar is provided in the rotating drum.

e. Action This invention produces fresh tea leaves that are well ventilated.
The tea leaves are heated to a temperature of around 30 to 50 ° C with a far-infrared heater that spreads them thinly in a room maintained at about 65 ° C and that can radiate evenly to the fresh tea leaf surface. , The water gradually decreased, but it did not get damp because of good ventilation, and the stems and leaves were evenly heated by the far-infrared heater, so it was exposed to strong sunlight. It withers rapidly as it does. Since the stem has more water and a smaller surface area than the leaves, it is more difficult to dry than the leaves even if it receives hot air, but far infrared rays have the characteristic that they are absorbed by the places with a lot of water. The tea leaves are withered evenly on the stems and leaves.

By the way, fresh tea leaves do not irradiate with far-infrared rays only by allowing hot air to pass through, and the moisture content of the surface is likely to decrease. . On the contrary, unless the hot air is permeated only by heating with the far-infrared heater, moisture evaporating from the fresh tea leaves is stagnant and rapid withering action cannot be performed.

As tea leaves wither, the aroma of wilting becomes stronger, the surface gloss disappears, and the tea leaves become softer, gradually promoting the oxidation (fermentation) of catechins. Then, the fermentation of the fresh tea leaves starts from the edges of the leaves and the veins of the leaves while producing a fermented aroma.
During this time, the green tea leaves are not damaged and are evenly heated by the irradiation of far infrared rays, resulting in homogeneous fermentation.

By the way, the product temperature of the fresh tea leaves is about 35 ° C. when the tea leaves are buds, about 40 ° C. for normal leaves, and about 45 ° C. for hard leaves. This is because the harder leaves have less oxidative enzymes and the fermentation is less likely to proceed, and the higher the product temperature, the more easily the fermentation proceeds. Therefore, the far-infrared heater and hot air temperature are adjusted so that the product temperature of the fresh tea leaves is maintained at the above value. Also,
The far-infrared heater described above, even if it is a mere infrared heater, can have the same function and effect.

The above-mentioned wilting and fermentation operations are carried out for about 30 to 60 minutes, and are terminated when the water content of the tea leaves decreases by about 15 to 25 ° C., and the edges and veins of the tea leaves are fermented and become brownish.

Next, a predetermined amount of the tea leaves thus withered and fermented is stored, and a batchwise rotary stirring operation is added. The predetermined amount means that the volume of tea leaves is about 1/5 to 1/2 of the volume of the rotary stirring means, and changes depending on the apparent specific gravity of fresh tea leaves.

Each time the tea leaves in the rotary drum are slowly agitated, the weights of the tea leaves give a light pressing force to each other, whereby the fermentation is evenly promoted and the fermented aroma is also benefited.

In the rotary drum, its exhaust temperature [approximately equal to the tea leaf temperature] is 40
If warm air (hot air) is supplied and heated to about ℃, fermentation of tea leaves will proceed easily, so the process time will be
It may be as short as 10 to 30 minutes. When supplying cold air, the process time is about 30 to 80 minutes. However, withdrawal / fermented aroma is generally better with cold air than with hot air. Further, if the fermentation is excessively advanced by the previous wilting and fermentation operations, the process time is shortened, and if the fermentation is not advanced, it is lengthened.

Fermentation of tea leaves spreads from the veins of the leaves to the surroundings gradually, but in appearance, a little green remains between the veins in the center of the leaves, and in the end, about half of the catechins are oxidized. Need to stop at. Therefore, the tea leaves are taken out from the rotary drum and sent to the next roasting step. When stir-fried and heated on an iron plate heated to about 200-400 ℃, the activity of oxidase in the tea leaves ceases and the fermentation does not proceed any further.

The above-mentioned rotary stirring operation is performed batchwise, and since the fermentation is promoted by the uniform pressing action by the weight of each other when stirring and dropping, tea leaves are uniformly and rapidly fermented. Proceed to step 1 to have an excellent withered fermented aroma.

By the way, in the second aspect of the invention, first, the tea leaves are thinly spread and heated by the far-infrared heater, and sequentially transferred by the transfer means, so that the tea leaves are gradually withered and continuously fermented. Next, the tea leaves that are taken out little by little are stored in a pool until they reach a predetermined amount, and they are stored in a rotating drum and processed at once, so there is some unevenness in the previous continuous wilting and fermentation operations. The unevenness is eliminated, and tea leaves that are uniformly withered and fermented are obtained.

Further, by automating the transfer means, the pool, and the loading / unloading of the rotary drum, it is easy to unmanned the operations of withering and fermenting fresh tea leaves.

f. Embodiment An embodiment of the present invention is shown in FIG. 1 and will be described with reference to the drawings. Consists of a wilting device A, a weighing pool B, and a fermentation device C,
Each is connected by a conveyor for loading and unloading, and the control device automatically carries out the loading of fresh tea leaves and the removal of fermented leaves.

The retracting device A is a caterpillar-shaped four-stage endless transportation zone (1) with a width of about 1 m, and a 700 W far-infrared heater (2) mounted on the first-stage and third-stage endless transportation zone (1), respectively. 40 ~ between the uniform heating device (3) consisting of three and each endless transportation zone (1)
A hot air generator (4) capable of supplying hot air of about 80 ° C at a total of about 10 m ³ / min, and these (1), (2), (3),
It comprises an airframe (5) surrounding (4), a ventilation fan (6) for ventilating the airframe (5), and the like. As shown in FIG. 1, each endless transportation zone (1) has a structure in which the caterpillar is vertically arranged at the other end to drop the freshly placed tea leaves, so that the introduced tea leaves are 8 Transferred to a stage.
Further, since the heating device (3) does not uniformly heat the fresh tea leaves that are spread and transferred by simply arranging the far-infrared heaters (2), good wilting / fermentation cannot be expected. Reflecting plates (7) and (8) are arranged above and below (2) so that even far infrared rays are uniformly irradiated to any part of the fresh tea leaves. (9), (1
0) is the fresh tea leaf inlet and outlet, respectively. Reference numeral (11) is a loading conveyor for thinly spreading and feeding fresh tea leaves into the loading port (9). (12), (13) and (14) are conveyors for respectively conveying the tea leaves taken out from the take-out port (10) to the weighing pool B, and only the conveyor (14) stops when the weighing pool B is full.

The weighing pool B includes a weighing mechanism capable of weighing 30 to 60 kg of tea leaves. (16) is a conveyor that receives the tea leaves of the weighing pool B and puts them into the next fermentation apparatus C.

Fermenter C has a cylindrical shape with a diameter of about 1.2 m and a length of about 1.2 m, and a rotating drum (20) with a bar (25) with a height of about 15 cm.
And a gas furnace (21) capable of generating hot air of about 40 to 80 ° C. in the rotary cylinder (20) as necessary, and the rotary cylinder (20)
It is composed of an exhaust blade (22) for exhausting the inside, and a drive section (23) for rotating the rotary drum (20) and the exhaust blade (22). (24) is a take-out conveyor that conveys the tea leaves taken out from the rotary drum (20) to the next step.

Therefore, the case of producing fresh tea leaves in early August will be described. Fresh tea leaves around this time are less fermentable than fresh tea leaves around May and June, but they are much easier to ferment than those after September.

In the wilting device A, the transfer speed of the endless transportation zone (1) is adjusted so that it takes 30 minutes from the input of the fresh tea leaves to the removal thereof, the thickness of the fresh tea leaves is 25 mm, and the room temperature is 45 to 50 ° C. Adjusted to each. As a result, the fresh tea leaves were kept at a temperature of about 40 ° C. immediately after being put into the tea leaves, and wilting and fermentation proceeded well. The weight loss at the time of extraction was 25%, the edges and veins of tea leaves became brownish, and wilt and fermented aromas were produced.

The tea leaves continuously and little by little withdrawn from the wilting device A are stored in the measuring pool B until the tea leaves reach 38 Kg, but the wilt and fermented aroma become stronger during the standing.

In the fermenter C, 38 kg of tea leaves are processed at one time. The combustion of the gas furnace is adjusted so that the exhaust gas temperature during the introduction of tea leaves is around 30 to 35 ° C. The rotation speed of the rotary cylinder (20) is 14 rpm. The treatment time of tea leaves was 20 to 30 minutes. Then, the tea leaves were further withered and fermented, and the aroma thereof became stronger. The weight of the tea leaves at the time of extraction was 35% less than that of the fresh tea leaves, and progressed to the extent that a slight green color remained between the central veins of the leaves. Good soft and soft tea leaves were obtained after uniform wilting and fermentation.

g. Effect As described above, according to the present invention, thin tea leaves are aerated with a small amount of hot air and evenly irradiated with far infrared rays, and the product temperature is maintained at about 30 to 50 ° C. Raw leaves are heated evenly on stems and leaves without stuffiness, and are rapidly withered and fermented as in strong sunlight.

In addition, since a predetermined amount of tea leaves thus withered and fermented is collected and rotated and stirred at one time, the tea leaves are subjected to a light pressing action due to the weight of each other, and the fermentation proceeds more uniformly and rapidly.

Therefore, the present invention is 1/3 compared to the conventional wilting and fermentation operations that are manually performed while being affected by the weather.
It is possible to perform the same withering and fermentation in a short time of ~ 1/4, and if these operations are mechanically performed, almost no human labor is required. In addition, it is possible to always perform uniform withering and fermentation regardless of the weather.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along line MM. A: Withdrawal device B: Weighing pool C: Fermentation device (1): Endless transportation zone (2): Far infrared heater (3): Heating device (4): Hot air generator (20): … Rotating body (25) ……

Claims (2)

[Claims] 1. Fresh tea leaves are thinly spread in a space maintained at a room temperature of about 35 to 65 ° C. by supplying a small amount of hot air and exhausting the hot air from the other, and the tea leaves are evenly distributed over the surface of the fresh tea leaves. A far-infrared heater designed to emit radiation heats fresh tea leaves so that the product temperature is around 30 to 50 ° C. to promote wilting and fermentation of the fresh tea leaves, and then collects a predetermined amount of such fresh tea leaves, A method for withering and fermenting fresh tea leaves by further rotating and stirring the mixture. 2. A fresh tea leaf inlet on one side and an outlet on the other side,
A transfer means for transferring tea leaves while being thinly spread is provided inside, and a far-infrared heater capable of uniformly radiating the surface is mounted on the transfer means, and a hot air generator capable of supplying a small amount of hot air is provided. And a means for withdrawing and fermenting fresh tea leaves, a pool for holding the tea leaves taken out from the withering means to a predetermined amount, and a cylindrical rotating drum for accommodating the tea leaves in a predetermined amount in the pool. In addition, the apparatus for withering and fermenting fresh tea leaves, which comprises fermenting means provided with a stirrer inside the rotary drum.